Image recording system using electronic light amplification and ultraviolet sensitive record



Feb. 15, 1966 3 235,658

R. M. LEVY IMAGE RECORDING SYSTEM USING ELECTRONIC LIGHT AMPLIFICATIONAND ULTRAVIOLET SENSITIVE RECORD Filed May 16, 1962 IMAGE DEVELOPEROPTICAL INTENSIFYING E gEfi Y 'fJ-F I AND FIXER SYSTEM AND CONVERTINGMATERIAL (HEAT OR l/ MEANs AMMONIA SOURCE) iv LIGHT sOuRcE 12 OPAQUECOPY 2 INVENTOR.

ATTORNEY? United States Patent ()ffice IMAGE RECORDING SYSTEM USINGELEC- TRQNIC LEGHT AMPLEFHCATHON AND ULTRAVIOLET SENSITIVE RECORD RobertM. Levy, Kalamazoo, Mich, assignor to Allied Paper Corporation, acorporation of Illinois Filed May 16, 1962, Ser. No. 195,169 18 Claims.(Cl. 178-63) This application relates generally to reproduction methods,systems and apparatus and more particularly to new and improvedreproduction methods, systems and apparatus adapted to provide rapiddirect positive copies from various types of subject matter onultraviolet sensitive materials.

Those skilled in the art are familiar with the present techniquesutilizing ultraviolet sensitive materials such as diazo-type, blueprint,Kalfax, bichromated colloids, Dyril and the like. These materials areall characterized by being extremely slow when judged by normalphotographic standards. For this reason, they generally are not utilizedin projection-reflection copy techniques, even with the most intenseultraviolet radiation energy sources. They also are characterized by thefact that they are not useful in contact reflex copy techniques. Hence,their utility has been restricted heretofore to contact copy methodsusing only translucent or transparent original graphic matter.

These ultra-violet sensitive materials, on the other hand, do possessmany advantages. In particular, they are relatively inexpensive toproduce, they produce direct positive copies, they are relativelyunaffected by visible light, X-rays and nuclear radiation, and theyrequire only exceedingly simple development processing followingexposure. Cumbersome darkroom methods therefore, are not required.

Other prior art techniques for copy reproduction utilizing differentsensitized materials are useful in actual practice, but they arecharacterized by inherent disadvantages which limit their desirabilityor range of use. For example, normal photographic techniques firstrequire the making of a negative and then a positive copy therefrom. Inaddition, conventional silver sensitized materials normally used in suchphotographic techniques are wet processed, requiring complex liquidchemicals for development and fixing, and are sensitive to nuclearradiation, X-rays, and the like as well as visible light, therebyrequiring the exercise of considerable care in storing, handling andprocessing.

In addition to the wet photographic techniques utilized for photocopyand other image reproduction, other techniques are known which arecharacterized by dry, electronic operation. The most commonly used ofsuch prior techniques include electrostatic printing systems of thexerographic type and heat sensitive printing systems of thethermographic type. Electrostatic printing systems form a latentelectrostatic image by the selective dissipation of a uniformelectrostatic charge previously placed upon a photoconductive surface,which latent image is developed by the application of suitableresin-based powders of opposite charge that subsequently are fixed,either upon the photoconductive surface or upon a substrate to which thepowder image is transferred. Thermographic printing systems form animage by direct exposure of a heat sensitive substrate to high intensityirradiation and must be protected from heat both prior and subsequent tothe formation of the image. Such prior art techniques have not provedentirely satisfactory as they are burdened by relatively high degrees ofcomplexity and cost in construction and operation, or by an inability tomake complete facsimile reproductions of objects of all types andcolors, or by their sensitivity to visible light and heat radiationwhich requires special handling procedures.

Accordingly, it is a general object of this invention to provide a newand improved general purpose reproduction method, system and apparatuswhich overcomes the disadvantages characteristic of the prior arttechniques.

It is a more specific object of this invention to provide a uniquemethod, system and apparatus for making facsimile reproductions whichare characterized by their relative simplicity and their flexibility inmaking rapid, and accurate facsimile reproductions of objects,documents, or the like, whether transparent, translucent or opaque.

In accordance with the features of one illustrative embodiment of thepresent invention, subject matter to be copied is illuminated by lowintensity visible radiations, as for example, from an ordinary tungstenlamp and the reflected image is transmitted by suitable optics to anelectronic image intensifying and converting apparatus. Such apparatus,in one preferred embodiment, may take the form of a high vacuum tubehaving an input photocathode sensitive to the visible light and emittingphotoelectrons to form an electron beam corresponding to the visiblelight image. The electron beam is focused and intensified byacceleration of the photoelectrons in a high potential field andimpinges upon a phosphor screen photoanode adapted to convert theelectron image into an ultraviolet image. This ultraviolet image then isused to expose ultraviolet sensitive material having a correspondingspectral sensitivity to form a latent positive image of the object to becopied. This latent positive image then is developed, as by heat,ammonia, or other means depending upon the sensitized material, toprovide an accurate, facsimile copy of the object.

Thus, it is another object of this invention to provide a new andimproved reproduction method, system and apparatus which converts avisible light image to an electron image, intensities the electron imageand converts it to an ultraviolet image, exposes ultraviolet sensitivematerial to said ultraviolet image to form a latent image, and developssaid latent image to provide an accurate direct positive copy.

It is still another object of this invention to provide such a new andimproved reproduction method, system and apparatus, as above, whereinthe ultraviolet image has spectral energy characteristics matched to thespectral absorption of the ultraviolet sensitive material, and does notrequire protection against ordinary visible light, X-rays, nuclearradiation, and the like.

It is a further object of this invention to provide such a new andimproved reproduction method, system and technique, as above, whereinthe ultraviolet sensitive material exposed to the ultraviolet image isdeveloped and permanently fixed by the application of heat, ammonia,alkaline coupler, or the like, and is adaptable to dry, liquid or vaportechniques, as desired.

In accordance with the features of an alternative embodiment of thisinvention, the image intensifying and converting means may take the formof a pair of spacedapart, transparent electrodes having a source of highfrequency potential connected thereto to establish a potential fieldtherebetween. Sandwiched between the spaced-apart electrodes is a thinfilm of a photoconductive material and a layer of an ultravioletelectroluminescent phosphor. Advantageously, these components comprisingthe image intensifying and converting means are assembled in closecontact with each other so as to form an integral, compact assembly.When a visible light image impinges on the photoconductive materialthrough one of the transparent electrodes, the impedance of thephotoconductive film changes in accordance with the character- Pa'tentedFeb. 1 5, 1 966 istics of the visible light image. This change inimpedance, in turn, causes changes to occur in the electrical fieldacross the phosphor layer to produce an ultraviolet image at the othertransparent electrode. Ultraviolet sensitive material, sensitive in thesame spectral range as the image, is positioned adjacent to said othertransparent electrode and is exposed to the ultraviolet image to form alatent image which may be developed as described above in accordancewith knwon techniques.

Therefore, it is another object of this invention to provide new andimproved facsimile reproduction apparatus which comprises an assembly ofa pair of spacedapart electrodes having a photoconductive film and anultraviolet phosphor layer sandwiched therebetween.

It is a further object of this invention to provide new and improvedimage reproduction apparatus, as above, wherein a high frequencypotential source is connected between said electrodes to establish apotential field such that the impedance changes in the photoconductivefilm in accordance with the impingement of a visible light image thereoncauses changes in the potential field to occur across the phosphor layerto produce an ultraviolet image for exposing an ultraviolet sensitivesubstrate.

It is a still further object of this invention to provide a new andimproved reproduction method, system and apparatus as above, which ischaracterized by its speed and flexibility of operation, and itsadaptability of use with various types of translucent, transparent, andopaque objects to be copied.

The novel features which are characteristic of the invention are setforth with particularity in the appended claims. The invention itself,however, both as to its organization and method of operation, togetherwith further objects and advantages thereof, will best be understood byreference to the following description taken in conjunction with theaccompanying drawing in which:

FIGURE 1 illustrates in block diagram form the method of operation andthe construction of an image reproducing system embodying the principlesof the present invention;

FIGURE 2 illustrates one illustrative embodiment of the invention whichutilizes a high vacuum image intensifying and converting tube as oneelement of the system; and

FIGURE 3 illustrates an alternative embodiment of the invention whichutilizes a compact, unitary assembly of transparent electrodes,photoconductive film, and ultraviolet electroluminescent phosphor layerin a high frequency potential field to provide intensification andconversion of the visible light image to an ultraviolet image.

Referring now to the drawing, and more particularly to FIGURE 1 thereof,there is shown an object which is the original from which thereproduction is to be made. In accordance with one of the highlyadvantageous features of this invention, the original object 10 may betransparent, translucent, or opaque, and if the object 10 takes the formof a document, the document may be printed on one or both sides withoutadversely affecting the operation of the invention. For purposes ofillustration, the object 10 will be described as a document bearing theprinted matter 12 on the upper surface thereof, although those skilledin the art will readily appreciate as this description proceeds, thatthe invention is not limited to use with a printed document but in fact,can be used to produce facsimile copies of any object from which avisible light image can be obtained and that the object may be a movingweb in a scanning system as well as a stationary object.

The visible light image of the printed matter 12 may be obtained throughthe use of any suitable visible light source such as natural light, atungsten source, etc. In the illustrative embodiment of FIGURE 1, thelight source 14 is shown as positioned above the printed matter 12 toform a reflected visible light image thereof, although it will beappreciated that if the objects 10 is formed of transparent ortranslucent material, the light source 14 may be positioned below theobject 10 for light transmission therethrough to form the visible lightimage to be reproduced.

The reflected visible light image from the printed matter 12 on theobject 10 is transmitted through a suitable optical system 16 to theinput of image intensifying and converting means 18. It will beappreciated by those skilled in the art that the optical system 16 maycomprise suitable prisms, mirrors, and optical lenses, as desired, fortransmitting the visible light image tothe image intensifying andconverting means 18. It also will be understood that, under ordinarycircumstances, the visible light image will be of relatively lowintensity when it impinges the image intensifying and converting means18.

In accordance with a feature of this invention, this relatively lowintensity visible light image is intensified at the image intensifyingand converting means 18, as by converting the visible light image to aphotoelectron image through the use of a photocathode having aphotoemissive surface and by subjecting the photoelectrons generated atthe photocathode to a relatively high potential for accelerating thephotoelectrons. The accelerated photoelectrons comprising theintensified photoelectron image impinge upon an ultraviolet emittingphosphor for converting the photoelectron image to a correspondingrelatively high intensity ultraviolet image. It will be appreciated thatthe intensity of the ultraviolet light image thus generated will bedependent upon the intensity of the visible light image transmitted tothe image intensifying and converting means 18 and upon the degree ofintensification of the photoelectron image within the image intensifyingand converting means 18.

The ultraviolet image at the output of the image intensifying andconverting means 18 then is caused to expose ultraviolet sensitivematerial, which in one use of the invention, may take the form of anultraviolet sensitive diazo paper 20 to form a latent image of theprinted matter to be copied.

In accordance with known techniques for developing latent images upondiazo paper, the diazo paper 20 then may be suitably developed to form afacsimile reproduction of the original graphic or other subject matter.As explained in greater detail hereinbelow, the latent image on thediazo paper may be developed by applying heat, ammonia, or liquidalkaline coupler, thereto, and the invention is not limited in its useto either heat development, ammonia development, or other types ofdevelopment, either in a wet or dry form. Ultraviolet sensitive diazomaterials suitable for use in the invention are available commercially,such as the ammonia vapor developable materials, and so-called moistdevelopable materials, both of which give dye images; heat developablematerials of the type which forms a bubble image such as the Kalvarmaterials sold by the Kalvar Corporation of New Orleans, Lousiana,bichromated colloids which gives a relief image after exposure andwashing with water, Dycril plastic which gives a relief image afterexposure and washing with dilute alkali, and direct positive ordinaryblueprint papers. Thus, it is clear that the use of the invention is notlimited to any specific types of ultraviolet sensitive materials andthat the exemplary materals discussed herein merely are illustrative ofsuch ultraviolet sensitive materials.

A specific illustrative embodiment of the invention is illustrated inFIGURE 2 of the drawing. As there shown, the object to be copied 10 isilluminated by the visible light source 14 to provide an incident,reflected, visible light image. This relatively feeble visible lightimage is transmitted by means of the optical system comprising the:prism 24 and the lens 26 to an image intensifying and. converting means18 where it is focused upon the photo-- cathode 28. The photocathode 28serves to generate: photoelectrons forming the photoelectron imagecorre: sponding to the visible light image which impinges upon thephotocathode. Various photoemissive materials suitable for use as thephotocathode 28 are known to those,

v skilled in the art, and for example, the photocathode 28advantageously may comprise oxidized cesium antimony or its equivalent.It is advantageous of course, to utilize a photocathode having aspectral response matched to the source of illumination.

As shown in the illustrative embodiment of FIGURE 2, the imageintensifying and converting means 18 may take the form of a magneticallyfocused high vacuum tube having the photocathode 28 at one end thereofand a photoanode or phosphor screen 30 spaced therefrom at the other endof the vacuum tube 18. Advantageously, a source of high potential 32,for example the source of DC. potential in the order of 25,000 volts, isconnected between the photocathode 28 and the photoanode 30 so as tocreate a high potential field in the vacuum tube for accelerating thephotoelectrons emitted by the photocathode 28.

In this illustrative embodiment, the image intensifying and convertingtube 18 advantageously may comprise a plurality of radial lens membersG1, G2, G3, G4, G5, G6, G7 and G8 successively positioned within theenvelope of tube 18, which lens members may take the form of stainlesssteel cylindrical shells for accelerating the photoelectron image fromthe photocathode 28 to provide the desired degree of intensification.This acceleration is effected by a voltage divider comprising aplurality of resistances 33 connected across the terminals of the highpotential source 32, the junctions of each pair of resistances beingconnected respectively to individual ones of said radial lens members,as shown in FIGURE 2.

The accelerated photoelectrons are focused on the photoanode phosphorscreen 30, either by suitable electrostatic focusing means or byelectromagnetic means, such as the electromagnet 35 shown adjacent theimage intensifying tube 18 in FIGURE 2. Those skilled in the art willappreciate that the function of the electromagnet 35 in this embodimentof the invention is to provide sharper focus of the photoelectron image.by spinning the electrons as they pass through the radial lens memberswithin the tube 18. These electrons end up at the exact point of focuson the photoanode 30'corresponding to the point of light impingement onthe photocathode 28.

In accordance with a feature of this invention, the photoanode phosphorscreen 30 is comprised of an ultraviolet cathodoluminescent phosphormaterial. One suchmaterial, which is known in the art as Pl6 phosphor,comprises calcium magnesium silicate which has been cerium activated.Thus, it will be appreciated, that the impingement of the intensifiedphotoelectron image on the phosphor screen 30 converts the electronimage to an ultraviolet image which in the illustrative example emitsenergy in the spectral range of approximately 3300 to 4500 Angstromswhich matches closely the ultraviolet absorption of commerciallyavailable diazo papers. It will further be appreciated that theintensity of the ultraviolet light image at the phosphor screen 30wi1lbe dependent upon the intensity of the visible light image transmittedto the image intensifying and converting means 18, upon the powersupplied, and upon the efficiency of the photocathode and photoanode.

Also, as shown in the FIGURE 2 embodiment, the high vacuum imageintensifying and converting tube 18 includes an aluminum backing 34 .onthe photocathode side of the phosphor screen 30. The purpose of thealuminum backing 34 is to prevent light feedback from the phosphorscreen 30 so that all the ultraviolet image is transmitted through theoutput lens system of the tube 18. This ultraviolet image is transmittedthrough a suitable lens system 36 or a fiber optic system on thephotoanode face (not shown) to impinge upon and expose the ultravioletsensitive surface 38 of a record sheet positioned on the backing plate40 or placed directly adjacent to the fiber optic tube face (not shown).In accordance with a feature of this invention, the energy absorptioncharacteristics of the ultraviolet sensitive surface 38 is matched tothe spectral energy output of the phosphor. The closer the match betweenthis absorption characteristic and the phosphor, the more effective thesystem. Therefore, in this embodiment the ultraviolet sensitive surfacehas a spectral sensitivity in the range of approximately 3300 to 4500Angstroms so that a latent image of the object to be copied is formed onthe ultraviolet sensitive material when it is exposed to the ultravioletimage.

Advantageously, the ultraviolet sensitive material may take the form ofa diazo paper in which the latent image may be developed by theapplication of heat, ammonia, or other means, in accordance withwell-known practices. Thus, if the ultraviolet sensitive material is inthe form of Kalvar paper, the latent image may be developed bytransporting the ultraviolet sensitive sheet 38 through the heatedrollers 42, or in the alternative, the ultraviolet sensitive sheet 38may be exposed to other heat sources such as infra-red lamps. Whereother types of ultraviolet sensitive papers are used, the latent imagemay be developed by similar heat sources, by ammonia vapor or by othermeans in accordance with known techniques.

If in the use of the invention, the efficiences of the photoanodephosphors are so low as to require relatively high degrees of energyabsorption by the copy to obtain full exposure, the temperature of thephotoanode phosphor may rise to an undesirable point. In this event, itis contemplated that the photoanode phosphor surface may be cooled, asby the fan 44, or alternatively cooled by any suitable means. Inaddition, a conductive coating can be applied to the photocathodesurface 28 to reduce resistivity and to increase the acceleration of thephotoelectrons generated by the photocathode. Still further, it iswithin the principles of this invention that the photoelectronacceleration may be improved by the use of high intensity pulsingaccelerating voltages.

In one embodiment of the invention, the image intensifying andconverting means 18 took the form of a high vacuum light imageintensifying tube manufactured by the Westinghouse Electric Corporationand similar to type WX-4480 which was magnetically focused and suppliedwith a 510 photocathode and a P-l6 phosphor. Manifestly, this particulartype of light image intensifier tube is merely one type of imageintensifying and converting means suitable for use in the inventiondisclosed herein, and the use of the invention is not limited to such aparticular type of light image intensifier tube.

FIGURE 3 illustrates an alternative embodiment of the invention whichutilizes a different type of image intensifying and converting means. Asthere shown, the object 10 to be copied is illuminated by means of thelight source 14 to provide a visible light image, as discussedhereinabove. This visible light image is transmitted and focused bymeans of the optical system comprising the prism 24 and lens 26 so as toimpinge upon the photocathode of the image intensifying and convertingassembly 18. In this particular embodiment, the image intensifying andconverting means 18 advantageously comprises a unitary assembly formedof a pair of spaced-apart transparent electrodes 46 and 48, which may beformed of glass covered with a transparent tin oxide layer 50. Themetallic layer 50 of each transparent electrode is connected to aterminal of a high frequency A.C. source 52 which, when the switch 54 isclosed, provides an alternating potential field between the spaced-apartelectrodes. Sandwiched between the spaced-apart electrodes, is a thinfilm 56 of the photoconductive material, which may be cadium sulphide.Adjacent the photoconductive film 56, there may be a layer of opaquedielectric material to prevent light feedback (not shown) and a layer ofultraviolet electroluminescent material 58, which for example, may takethe form of an activated zinc sulphide or the like. As shown in FIGURE3, the spaced-apart transparent electrodes, the photoconductive film,and the ultraviolet phosphor layer are assembled in a compact unitaryassembly which in actual practice, can be a relatively thin andlightweight arrangement. A sheet of ultraviolet sensitive material 38 ispositioned adjacent the electrode 48, for exposure by the ultravioletimage in the manner described hereinbelow.

Thus, in the operation of the invention, the incident or reflectedvisible light image impinging upon the photoconductive film 56 causesits impedance to be changed in accordance with the characteristics ofthe visible light image. This change in impedance causes charges tooccur in the electrical field across the phosphor layer 58 to produce anultraviolet light image at the transparent electrode 48 adjacent theultraviolet sensitive material 38. It will be appreciated that thedegree of amplification of the image in this embodiment is a function ofthe applied voltage from the source 52, the intensity of the inputvisible light image from the optical light system and the eflicienciesof the photoconductor and the phosphor.

Thus, there is described and illustrated hereinabove a new and improvedmethod, system and apparatus for facsimile reproduction of subjectmatter. This invention has the advantage of speed, low cost, accuratereproduction from any object, whether transparent, translucent oropaque, and of the use of ultraviolet sensitive materials which can bedeveloped by heat, ammonia, or other means and which materials arerelatively unaffected by visible light, X-rays, nuclear radiation andthe like.

While there has ben shown and described a specific embodiment of thepresent invention, it will, of course, be understood that variousmodifications and alternative constructions may be made withoutdeparting from the true spirit and scope of the invention. Therefore, itis intended by the appended claims to cover all such modifications andalternative constructions as fall within their true spirit and scope.

What is claimed as the invention is:

1. The improvement of apparatus for making facsimile reprodctions of anobject to be copied comprising the combination of optical means fortransmitting a visible light image of the object to be copied,electronic image intensifying and converting apparatus including aphotocathode having a photoemissive surface for receiving saidtransmitted visible light image and for generating photoelectronsforming a corresponding electron image, a phosphor screen photoanodespaced from said photocathode, a source of high potential connectedbetween said photocathode and photoanode for accelerating saidphotoelectrons to intensify said photoelectron image, said phosphorscreen photoanode being effective to convert said photoelectron image toan ultraviolet image when the intensified photoelectron image impingesthereon, ultraviolet sensitive material having a spectral sensitivity inthe spectral range of said ultraviolet image and operatively associatedwith said electronic image intensifying and converting apparatus forreceiving said ultraviolet image to form a latent image of said objectto be copied and means for developing said latent image to provide avisible reproduction of said object.

2. The improvement of aparatus for making facsimile reproductions of anobject to be copied comprising the combination of optical means fortransmitting a visible light image of the object to be copied,electronic image intensifying and converting apparatus including aphotocathode having a photoemissive surface for receiving saidtransmitted visible light image and for generating photoelectronsforming a corresponding electron image, a phosphor screen photoanodespaced from said photocathode, a source of high potential connectedbetween said photocathode and photoanode for accelerating saidphotoelectrons to intensify said photoelectron image, said phosphorscreen photoanode being effective to convert said photoelectron image toan ultraviolet image when the intensifted photoelectron image impingesthereon, utraviolet sensitive material having a spectral sensitivity inthe spectral range of ultraviolet image and operatively associated 8with said electronic image intensifying and converting apparatus forreceiving said ultraviolet image to form a latent image of said objectto be copied and a source of heat adapted to apply heat to saidultraviolet sensitive material for developing said latent image toprovide a visible reproduction of said object.

3. The improvement of apparatus for making facsimile reproductions of anobject to be copied comprising the combination of optical means fortransmitting a visible light image of the object to be copied,electronic image intensifying and converting apparatus including aphotocathode having a photoemissive surface for receiving saidtransmitted visible light image and for generating photoelectronsforming a corresponding electron image, a phosphor screen photoanodespaced from said photocathode, a source of high potential connectedbetween said photocathode and photoanode for accelerating saidphotoelectrons to intensify said photoelectron image, said phosphorscreen photoanode being effective to convert said photoelectron image toan ultraviolet image when the intensified photoelectron image impingesthereon, a sheet of ultraviolet sensitive material having a spectralsensitivity in the spectral range of said ultraviolet image andoperatively associated with said electronic image intensifying andconverting apparatus for being exposed to said ultraviolet image to forma latent image of said object to be copied, a source of heat forapplying heat to said sheet to develop said latent image to provide avisible reproduction of said object, and sheet transport means formoving said exposed sheet into heat receiving relationship with saidsource of heat.

4. The improvement in accordance with claim 3 wherein said sheettransport means comprises heated friction rollers.

5. The improvement of apparatus for making facsimile reproductions of anobject to be copied comprising the combination of optical means fortransmitting a visible light image of the object to be copied,electronic image intensifying and converting apparatus for receivingsaid transmitted visible light image and for generating photoelectronsforming a cor-responding electron image, a source of high potentialconnected to said apparatus for accelerating said photoelectrons tointensify said photoelectron image, said apparatus comprising a phosphorscreen effective to convert said photoelectron image to an ultravioletimage when the intensified photoelectron image impinges thereon,ultraviolet sensitive material having a spectral sensitivity in thespectral range of said ultraviolet image and operatively associated withsaid electronic image intensifying and converting apparatus for beingexposed to said ultraviolet image to form a latent image of said objectto be copied, and means for developing said latent image to provide avisible reproduction of said object.

6. The improvement in accordance with claim 5 wherein said last-namedmeans comprises a source of heat adapted to develop said latent image byapplying heat to said exposed material.

7. The improvement in accordance with claim 5 wherein said last-namedmeans comprises a source of ammonia adapted to develop said latent imageby applying ammonia to said exposed material.

8. The improvement of apparatus for making facsimile reproductions of anobject to be copied comprising the combination of electronic imageintensifying and converting apparatus for receiving the visible lightimage and for generating photoelectrons forming a corresponding electronimage, a source of potential connected to said apparatus foraccelerating said photoelectrons to intensify said photoelectron image,said apparatus comprising means effective to convert said intensifiedphotoelectron image to an ultraviolet image, ultraviolet sensitivematerial having a special sensitivity in the spectral range of saidultraviolet image and operatively associated with said electronic imageintensifying and converting 9 apparatus for receiving said ultravioletimage to form a latent image of said object to be copied and means fordeveloping said latent image to provide a visible reproduction of saidobject 9. The improved method of making facsimile reproductions of anobject comprisingthe steps of forming a visible light image of an objectto be copied, transmitting said visible light image through a suitableoptical system to an electronic intensifying andconverting apparatuscapable of converting said visible light image to a correspondingelectron image and intensifying said electron image, causing theintensified, electron image to impingeupon a suitably, coated surface toconvert said electronimage to a corresponding ultraviolet light image,and having an intensity dependent'upon the intensity of the visiblelight image transmitted to said apparatus, and upon the degree ofintensification of said electron image within said apparatus, causingthe ultraviolet light image from said apparatus to impinge uponultraviolet sensitive material having a spectral sensitivity in thespectral range of said ultraviolet light image to form a latent image ofthe object to be copied, and developing said latent image on theultraviolet sensitive material to form a visible copy of said object.

10. The improved method of making facsimile reproductions of an objectcomprising the steps of forming a visible light image of an object to becopied, transmitting said visible light image through a suitable opticalsystem to an electronic intensifying and converting apparatus capable ofconverting said visible light image to a corresponding electron imageand intensifying said electron image, causing the intensified electronimage to impinge upon a suitably coated surface to convert said electronimage to a corresponding ultraviolet light image, and having anintensity dependent upon the intensity of the visible light imagetransmitted to said apparatus and upon the degree of intensification ofsaid electron image within said apparatus, causing the ultraviolet lightimage from said apparatus to impinge upon ultraviolet sensitive materialhaving a spectral sensitivity in the spectral range of said ultravioletlight image to form a latent image of the object to be copied, andapplying heat to said ultraviolet sensitive material to develop saidlatent image and form a visible copy of said object on said material.

11. The improved method of making facsimile reproductions of an objectcomprising the steps of forming a visible light image of an object to becopied, transmitting said visible light image through a suitable opticalsystem to an electronic intensifying and converting apparatus capable ofconverting said visible light image to a corresponding electron imageand intensifying said electron image, causing the intensified electronimage to impinge uopn a suitably coated surface to convert said electronimage to a corresponding ultraviolet light image, and having anintensity dependent upon the intensity of the visible light imagetransmitted to said apparatus and upon the degree of intensification ofsaid electron image within said apparatus, causing the ultraviolet lightimage from said apparatus to impinge upon ultraviolet sensitive diazomaterial having a spectral sensitivity in the spectral range of saidultraviolet light image to form a latent image of the object to becopied, and applying ammonia to said ultraviolet sensitive diazomaterial to develop said latent image and form a visible copy of saidobject on said diazo material.

12. The improved method of facsimile reproductions of an objectcomprising the steps of forming a visible light image of an object to becopied, converting said visible light image to a corresponding electronimage and intensifying said electron image, converting the intensifiedelectron image to a corresponding ultraviolet light image, causing theultraviolet light image to impinge upon ultraviolet sensitive materialhaving a spec tral sensitivity in the spectral range of said ultravioletlight image to form a latent image of the object to be 10 copied, anddeveloping said latent image on the ultraviolet sensitive material toform a visible copy of said object.

13. The improved method of making facsimile reproductions of an objectcomprising the steps of forming a visible light image of an object to becopied, converting said visible light image to a corresponding electronimage and intensifying said electron mage, converting the intensifiedelectron image to a corresponding ultraviolet light image, causing theultraviolet light image to impinge upon ultraviolet'sensitive diazomaterial having a spectral sensitivity in the spectral range of saidultraviolet light image to form a latent image of theojbect to becopied, and applying heat to said ultraviolet sensitive diazo materialto develop said latent image and form a visible copy of said object ofsaid diazo material.

14. The improved method of reproducing a visible light image of anobject comprising the steps of forming a visible light image of anobject to be copied, converting said visible light image to acorresponding electron image and intensifying said electron image,converting the intensified electron image to a corresponding ultravioletlight image, causing the ultraviolet light image to impinge uponultraviolet sensitive diazo material having a spectral sensitivity inthe spectral range of said ultraviolet light to form a latent image ofthe object to be copied, and applying ammonia to said ultravioletsensitive diazo material to develop said latent image and form a visiblecopy of said object on said diazo material.

15. The improved method of reproducing a visible light image of anobject comprising the steps of forming a visible light image of anobject to be copied, transmitting said visible light image through asuitable optical system to an electronic intensifying and convertingapparatus, of the type having a thin film of photoconductive materialand a layer of ultraviolet electroluminescent phosphor sandwichedbetween a pair of transparent electrodes, causing the visible lightimage to impinge on said thin film of photoconductive material to changeits impedance and thereby change the electrical field occurring acrossthe phosphor layer in accordance with said visible light image forgenerating corerspon-ding ultraviolet light image, causing theultraviolet light image from said phosphor layer to impinge uponultraviolet sensitive material positioned adjacent one transparentelectrode and having a spectral sensitivity in the spectral range ofsaid ultraviolet light image to form a latent image of the object to becopied, and developing said latent image on the ultraviolet sensitivematerial to form a visible copy of said object.

16. The improvement of apparatus for making facsimile reproductions ofan object to be copied comprising the combination of optical means fortransmitting a visible light image of the object to be copied,electronic image intensifying and converting apparatus including a pairof spaced-apart transparent electrodes having sandwiched therebetween athin film of photoconductive material and an ultravioletelectroluminescent phosphor layer, a source of high potential connectedbetween said pair of spaced-apart transparent electrodes, said opticalmeans causing said visible light image to impinge on said thin film ofphotoconductive material to change its impedance in a mannercorresponding to said visible light image and thereby cause changes tooccur in the electrical field across said phosphor layer to provide anultraviolet image, ultraviolet sensitive material 'having a spectralsensitivity in the spectral range of said ultraviolet image positionedadjacent one transparent electrode of said electronic image,intensifying and converting apparatus for receiving the ultravioletimage to form a latent image of said object to be copied and means fordeveloping said latent image to provide a visible reproduction of saidobject.

17. The improvement of apparatus for making facsimile reproductions ofan object to be copied comprising 1 1 the combination of electronicimage intensifying and converting apparatus including a pair ofspaced-apart transparent electrodes having a photoconductive film and anultraviolet electroluminescent phosphor layer positioned therebetween, asource of high potential connected to said transparent electrodes,optical means for causing a visible light image of the object to becopied to impinge on one of said transparent electrodes to change theimpedance of said photoconductive film and for causing charges to occuracross said phosphor layer in a manner corresponding to said visiblelight image, the occurrence of charges across said phosphor layer beingeffective to generate an ultraviolet image, ultraviolet sensitivematerial having a spectral sensitivity in the spectral range of saidultraviolet image positioned adjacent the other transparent electrode ofsaid electronic image intensifying and converting apparatus forreceiving said ultraviolet image to 12 form a latent image of saidobject to be copied and means for developing said latent image toprovide a visible reproduction of said object.

18. The improvement in accordance with claim 17 wherein saidphotoconductive film is comprised of cadmium sulphide and said phosphorlayer is comprised of zinc sulphide.

References Cited by the Examiner UNITED STATES PATENTS 2,921,513 1/1960Frantz 9577.5 2,974,369 3/1961 Orthuber 313108.1 3,027,822 4/1962 Frantz9589 3,077,150 2/1963 Schaifert 954.5

DAVID G. REDINBAUGH, Primary Examiner.

12. THE IMPROVED METHOD OF FACSIMILE REPRODUCTIONS OF AN OBJECTCOMPRISING THE STEPS OF FORMING A VISIBLE LIGHT IMAGE OF AN OBJECT TO BECOPIED, CONVERTING SAID VISIBLE LIGHT IMAGE TO A CORRESPONDING ELECTRONIMAGE AND INTENSIFYING SAID ELECTRON IMAGE, CONVERTING THE INTENSIFIEDELECTRON IMAGE TO A CORRESPONDING ULTRAVIOLET LIGHT IMAGE, CAUSING THEULTRAVIOLET LIGHT IMAGE TO IMPINGE UPON ULTRAVIOLET SENSITIVE MATERIALHAVING A SPECTRAL SENSITIVITY IN THE SPECTRAL RANGE OF SAID ULTRAVIOLETLIGHT IMAGE TO FORM A LATENT IMAGE OF THE OBJECT TO BE COPIED, ANDDEVELOPING SAID LATENT IMAGE ON THE ULTRAVIOLET SENSITIVE MATERIAL TOFORM A VISIBLE COPY OF SAID OBJECT.